wip: feat: Just use straight.el...

Every Nixy solution I could find or conceive had too many points spread across
these various facets:
  - Flimsy (emacsWithPackagesFromUsePackage)
  - Inelegant (builtins.exec, manual listings)
  - Inflexible (emacsWithPackagesFromUsePackage)
  - Otherwise unergonomic (everything }:D)

Straight.el is sufficiently declarative, flexible, and Nix-friendly without
blindly bowing down to the imperialist NixOS user.  Now, Convenience and
ergonomics shan't be forsaken for the dogma that is total Nixation.

README.org

@@ -364,3 +364,4 @@ Following is a subset of the many places I've learnt from.
 - [cite:@zaynetdinov2024you]
 - [[https://prelude.emacsredux.com/en/stable/][Emacs Prelude]]
 - [[https://github.com/doomemacs/doomemacs][Doom Emacs]]
+- [[https://cce.whatthefuck.computer/cce][Ryan Rix's Complete Computing Environment]]

modules/home/impermanence.nix

@@ -18,6 +18,28 @@ in {
         default = [];
         type = types.listOf types.anything;
       };
+
+      cache = {
+        directories = mkOption {
+          description = ''
+            While functionally identical to `directories` (at the moment),
+            `cache.directories` carries additional semantics: these directories
+            /can/ be erased, but typically /shouldn't/ be.
+          '';
+          default = [];
+          type = types.listOf types.anything;
+        };
+
+        files = mkOption {
+          description = ''
+            While functionally identical to `files` (at the moment),
+            `cache.files` carries additional semantics: these files /can/ be
+            erased, but typically /shouldn't/ be.
+          '';
+          default = [];
+          type = types.listOf types.anything;
+        };
+      };
     };
   };
 
@@ -25,8 +47,8 @@ in {
     home.persistence = {
       "/persist/home/${config.home.username}" = {
         allowOther = true;
-        directories = cfg.directories;
+        directories = cfg.directories ++ cfg.cache.directories;
-        files = cfg.files;
+        files = cfg.files ++ cfg.cache.files;
       };
     };
   };

users/crumb/programs/emacs.nix

@@ -17,8 +17,8 @@ let
 
   # Create a new instance of nixpkgs with emacs-overlay applied. This is a
   # little unorthodox, but we do it
-  #   1. for the sake of organisation — For pure aesthetics and a clean codebase, I want
+  #   1. for the sake of organisation — For pure aesthetics and a clean
-  #      everything Emacs to stay in this file;
+  #      codebase, I want everything Emacs to stay in this file;
   #   2. and, there's simply no need to leak emacs-overlay's packages into the
   #      global nixpkgs instance when nothing else is using it!
   pkgs' = import inputs.nixpkgs {
@@ -26,20 +26,32 @@ let
     overlays = [ emacs-overlay ];
   };
 
-  my-emacs = pkgs'.emacsWithPackagesFromUsePackage {
+  straightBaseDir = "${config.xdg.dataHome}/straight";
-    config = ./emacs/init.el;
+
-    defaultInitFile = false;
+  emacsWrapper = pkgs.symlinkJoin {
-    package = emacsPackage;
+    name = "emacs-wrapper";
-    alwaysEnsure = true;
+    paths = [ emacsPackage ];
-  };
+    buildInputs = [ pkgs.makeWrapper ];
-in {
+    postBuild = ''
-  programs.emacs = {
+      for i in $out/bin/emacs-*; do
-    enable = true;
+        wrapProgram "$i" \
-    package = my-emacs;
+          --add-flags "--init-directory \"${emacsConfigDir}\""
-    extraConfig = ''
+      done
-      (load (file-name-concat "${emacsConfigDir}" "init"))
     '';
   };
+in {
+  sydnix.impermanence.cache.directories = [ straightBaseDir ];
+  home.packages = [ emacsWrapper ];
+
+  home.sessionVariables.EMACS_STRAIGHT_BASE_DIR = straightBaseDir;
+
+  # programs.emacs = {
+  #   enable = true;
+  #   package = emacsPackage;
+  #   # extraConfig = ''
+  #   #   (load (file-name-concat "${emacsConfigDir}" "init"))
+  #   # '';
+  # };
 
   services.emacs = {
     enable = true;

users/crumb/programs/emacs/early-init.el

@@ -0,0 +1,3 @@
+;;; early-init.el -*- lexical-binding: t; -*-
+
+(setq package-enable-at-startup nil)

users/crumb/programs/emacs/init.el

@@ -1,6 +1,32 @@
 ;; -*- lexical-binding: t; -*-
 
-(require 'use-package-ensure)
+(defvar bootstrap-version)
-(setq use-package-always-ensure t)
 
-(use-package evil)
+(setq straight-base-dir
+      (or (getenv "EMACS_STRAIGHT_BASE_DIR")
+          (error "Cannot initialise straight: $EMACS_STRAIGHT_BASE_DIR is undefined!")))
+
+(let ((bootstrap-file
+       (file-name-concat straight-base-dir
+                         "repos/straight.el/bootstrap.el"))
+      (bootstrap-version 7))
+  (unless (file-exists-p bootstrap-file)
+    (let* ((url "https://raw.githubusercontent.com/radian-software/straight.el/develop/install.el")
+           (url-buffer (url-retrieve-synchronously
+                        url 'silent 'inhibit-cookies)))
+      (with-current-buffer url-buffer
+        (goto-char (point-max))
+        (eval-print-last-sexp))))
+  (load bootstrap-file nil 'nomessage))
+
+(setq straight-use-package-by-default t)
+
+(use-package evil
+  :init
+  (setq evil-want-minibuffer t)
+  :config
+  (evil-mode 1))
+
+(use-package which-key
+  :config
+  (which-key-mode 1))